Our long-term goals are to define the molecular mechanisms by which fascin controls cancer metastasis and progression. Cancer metastasis involves the dissemination of cancer cells from primary tumor to distant organ, and the expansion of disseminated metastatic cells to form secondary tumor. It has been well established that the actin cytoskeleton is frequently dysregulated to promote cancer cell motility, invasiveness during metastatic dissemination. However, the post-dissemination role of the actin cytoskeleton in cancer metastasis is largely unexplored. Fascin is the most frequently overexpressed actin binding protein in metastatic cancer, and its overexpression is uniformly associated with metastatic disease, aggressive clinical course and shorter survival across different cancer types. It is generally thought that fascin drives cancer metastasis by strengthening the actin cytoskeleton and promoting cell motility. In preliminary studies conducted in NSCLC models, we discovered a novel role for fascin in promoting metastatic colonization and expansion and augmenting cancer cell stemness by remodeling mitochondrial actin filaments. We propose that fascin enhances the self-renewal of cancer stem-like cell and metastatic expansion through a novel fascin-mitochondria-AMPK-YAP/TAZ pathway. We will build on these exciting preliminary findings to investigate the functional role of fascin- mediated remodeling of mitochondrial actin filaments in Aim 1. We will then define the role of the AMPK- YAP/TAZ pathway in fascin-mediated augmentation of cancer cell stemness in Aim 2. In Aim 3 we will determine the novel mitochondrial role of fascin and mitochondrial actin filaments in fascin-mediated NSCLC metastasis, and will explore the feasibility to inhibit cancer cell stemness and metastatic recurrence by targeting fascin. The success of proposed studies will cause a paradigm-shift in our understanding of the dysregulated actin cytoskeleton in metastatic progression, and will potentially provide novel avenues to prevent NSCLC metastatic recurrence.